A large study evaluating the combination of once-only immunochemical faecal occult blood testing, with flexible sigmoidoscopy (but not colonoscopy) for those with a positive test, showed a 32% reduction in rectal cancer mortality, but no reduction in overall mortality or colon cancer-specific mortality, at 8-year follow-up.

A total of 4 Level II RCTs compared flexible sigmoidoscopy as a screening modality with no screening, and reported a combined 28% reduction in colorectal cancer-specific mortality in those randomised to screening after nearly 11 years of follow-up. This benefit in colorectal cancer-specific mortality was attributed only to a reduction in distal colorectal cancer-specific mortality and not proximal colorectal cancer-specific mortality. Most trials provided a once-only flexible sigmoidoscopy as the screening test.

No high-level RCTs were found that compared screening with colonoscopy, CT colonographyAlso known as virtual colonoscopy, a medical imaging procedure that uses low dose radiation CT scanning to obtain an interior view of the colon (the large bowel) that is otherwise only seen with a more invasive procedure where an endoscope is inserted into the rectum and passed through the entire colon., faecal DNA biomarkers, or blood or plasma cancer-specific biomarkers such as DNA, with no screening.

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Only one RCTA study in which people are allocated at random (by chance alone) to receive one of several clinical interventions. One of these interventions is the standard of comparison or control. (NORCCAP) reported the combination of two screening modalities, flexible sigmoidoscopy and immunochemical faecal occult blood testing (iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin.). The overall reduction in colorectal cancer-specific mortality was only statistically significant for those who had flexible sigmoidoscopy and iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin. (HR = 0.62, p = 0.01) and not for flexible sigmoidoscopy alone (HR = 0.84, p = 0.30).

ScreeningPerforming tests to identify disease in people before any symptoms appear. test accuracy (PSC1b)

iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin. performed best at detection of colorectal cancer (when compared to a colonoscopy reference standard), and was also able to detect a proportion of advanced adenomas.

There is insufficient evidence to determine how the diagnostic performance of iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin. or biomarker assays may alter with participant age, sex, or risk of colorectal cancer.

iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin. every year in people aged 50–74 years

once-only colonoscopy screening at age 50 years combined with iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin. every 2 years in people aged 52–74

colonoscopy screening every 10 years at ages 55, 65 and 75 years

iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin. screening every 2 years at age 50–74 years, with or without adjunct flexible sigmoidoscopy (either at age 50 years or at ages 54, 64 and 74 years) for individuals with negative iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin..

Analysis based on early data from cross-sectional studies also suggested that screening with a faecal DNA assay every 2 years may be effective if emerging evidence supports the assumed test characteristics.

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The current National Bowel Cancer Screening ProgramAn Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease. (NBCSPThe National Bowel Cancer Screening Program. An Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease.) strategy (iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin. every 2 years at age 50–74 years) is associated with predicted reductions of 52% in colorectal cancer incidence and 75% in colorectal cancer-specific mortality in perfectly adherent people. Overall, the most effective strategies (as noted above) were associated with a 52–67% reduction in colorectal cancer incidence and 75–82% reduction in colorectal cancer mortality, compared with no screening, given perfect adherence.

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The incremental cost-effectiveness (ICER) analysis identified five strategies that represented the best value for money of all the available strategies assessed (i.e. strategies found to cost the least among all strategies with similar or higher effectiveness), but only two of these would be cost-effective in Australia under all scenarios, given the indicative willingness-to-pay threshold of A$50,000 per life–year saved:

CT colonographyAlso known as virtual colonoscopy, a medical imaging procedure that uses low dose radiation CT scanning to obtain an interior view of the colon (the large bowel) that is otherwise only seen with a more invasive procedure where an endoscope is inserted into the rectum and passed through the entire colon. every 10 years

iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin. every 2 years at age 50–74 years (the current program).

However, analysis for CT colonographyAlso known as virtual colonoscopy, a medical imaging procedure that uses low dose radiation CT scanning to obtain an interior view of the colon (the large bowel) that is otherwise only seen with a more invasive procedure where an endoscope is inserted into the rectum and passed through the entire colon. screening was based on more limited evidence for cross-sectional accuracy and there is a lack of evidence for longitudinal outcomes (long-term benefit). In the modelled analysis, the current NBCSPThe National Bowel Cancer Screening Program. An Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease. was the most effective of these two strategies.

iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin. screening every year was not found to be cost-effective, with an ICER of > $100,000 per life–year saved.

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The ICER for the current NBCSPThe National Bowel Cancer Screening Program. An Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease. (iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin. screening every 2 years), compared with the next most effective strategy (CT colonographyAlso known as virtual colonoscopy, a medical imaging procedure that uses low dose radiation CT scanning to obtain an interior view of the colon (the large bowel) that is otherwise only seen with a more invasive procedure where an endoscope is inserted into the rectum and passed through the entire colon.) on the cost-effectiveness frontier, was A$6,412-33,535 per life–year saved (depending on participation), taking into account all the other strategies included in the analysis.

This is not the same as the cost-effectiveness ratio (CER) of the current NBCSPThe National Bowel Cancer Screening Program. An Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease. compared with no screening (estimated at approximately $2,000–3,000 per life–year saved).

Each of these estimates provides a measure of the cost-effectiveness of the current NBCSPThe National Bowel Cancer Screening Program. An Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease., but the ICER considers a range of other, theoretically possible, options. Whichever measure is used, the current NBCSPThe National Bowel Cancer Screening Program. An Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease. was found to be cost-effective.

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The current NBCSPThe National Bowel Cancer Screening Program. An Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease. (iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin. screening every 2 years) requires 56 colonoscopies to prevent one colorectal cancer death, assuming 100% adherence to screening recommendations. No other strategy was found to have both fewer colorectal cancer deaths and fewer colonoscopies than iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin. every 2 years, implying that the current NBCSPThe National Bowel Cancer Screening Program. An Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease. has an optimal balance of benefits and harms.

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ScreeningPerforming tests to identify disease in people before any symptoms appear. age (PSC1d)

To date, no published RCTs have reported outcomes related to colorectal cancer screening-specific outcomes in those less than 50 years of age, or greater than 75 years of age.

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ScreeningPerforming tests to identify disease in people before any symptoms appear. with iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin. once every two years between 50 and 74 years (the current NBCSPThe National Bowel Cancer Screening Program. An Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease.) was predicted to reduce colorectal cancer incidence by 52% and reduce colorectal cancer mortality by 74%, compared to no screening (assuming perfect adherence).

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Compared to the current NBCSPThe National Bowel Cancer Screening Program. An Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease., lowering the screening start age to 40 or 45 years would result in additional reductions of 2–6 percentage points in colorectal cancer incidence and 2–9 percentage points in colorectal cancer-specific mortality, in all participation scenarios considered.

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Extending the age of ceasing screening to 79 or 84 years would result an additional reduction of 1–2 percentage points in colorectal cancer incidence and 2–5 percentage points in colorectal cancer mortality.

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When considering cost-effectiveness only for those strategies involving iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin. every 2 years, but with different age ranges, four strategies were found to have the best value for money of all the available strategies assessed (i.e. strategies found to cost the least among all strategies with similar or higher effectiveness).

In context of an indicative willingness-to-pay threshold of A$50,000 per life–year saved in Australia, only two were found to be cost-effective in all participation scenarios: the current program (ICER $4,264–8,075 per life–year saved) and screening at 45–74 years (ICER $19,451–40,813 per life–year saved).

Extending the screening end age to 79 or 84 years was not found to be cost-effective in this analysis.

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Although potentially cost-effective, lowering the screening start age to 45 years was predicted to be associated with a less favourable ratio of benefits to harms than the current program. The number-needed-to-colonoscope (NNC) for the current program for each death prevented is 39–56, whereas the NNC for each extra death prevented by starting at age 45 years is 67–375 (depending on participation).

At current levels of participation, starting from age 45 years would be associated with an additional 67 colonoscopies for each additional death prevented, compared with an NNC of 39 colonoscopies per death prevented for the existing program.

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Starting at age 45 years would increase the demand for colonoscopy services by 7–14% (depending on participation).

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The effect of starting screening earlier is amplified in imperfect adherence scenarios because the increase in deaths prevented is primarily due to an overall increase in the number of those screened at least once in a lifetime at any age (i.e. being screened at least once is the major determinant of outcome).

ScreeningPerforming tests to identify disease in people before any symptoms appear. from age 50 to age 74 years is more cost effective than screening people in their forties.

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N/A: not applicable

^NHMRC classification of levels of evidence does not currently encompass modelling studies.

Overall population screening strategy

The recommended strategy for population screening in Australia, directed at those at average risk of colorectal cancer and without relevant symptoms, is immunochemical faecal occult blood testing every 2 years, starting at age 50 years and continuing to age 74 years.

Frequency of testing

Population screening for colorectal cancer using immunochemical faecal blood testing every 2 years is recommended. It is not recommended that the frequency of screening within the NBCSPThe National Bowel Cancer Screening Program. An Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease. be increased to yearly.

Although modelling indicated that it may be cost-effective, starting screening at age 45 is not recommended for population screening because there is a much less favourable ratio of benefits to harms than for 50–74 years.

Consensus-based recommendationA recommendation formulated in the absence of quality evidence, after a systematic review of the evidence was conducted and failed to identify admissible evidence on the clinical question.

Resources should be invested in increasing participation in the existing NBCSPThe National Bowel Cancer Screening Program. An Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease. target age group of 50–74, rather than by lowering the starting age of screening, to optimise the balance of effectiveness, cost-effectiveness and ratio of benefits to harms.

Consensus-based recommendationA recommendation formulated in the absence of quality evidence, after a systematic review of the evidence was conducted and failed to identify admissible evidence on the clinical question.

In people aged 45–49 years who request screening after being fully informed of the benefits and harms of testing, general practitioners (GPs) could offer an immunochemical faecal occult blood test every 2 years during the lead-up to the first routine invitation by the NBCSPThe National Bowel Cancer Screening Program. An Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease. at age 50 years.

Practice pointA recommendation on a subject that is outside the scope of the search strategy for the systematic review, based on expert opinion and formulated by a consensus process.

Encouragement by GPs and practice staff substantially boosts participation in colorectal cancer screening. Patient endorsement letters in advance of receiving a test kit, the use of GPA medical professional who treats acute and chronic illnesses and provides preventive care and health education to a wide range of patients. reminder systems and practice audit are approaches likely to improve participation rates. Increased participation in the NBCSPThe National Bowel Cancer Screening Program. An Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease. will increase the program’s effectiveness and cost-effectiveness.

Practice pointA recommendation on a subject that is outside the scope of the search strategy for the systematic review, based on expert opinion and formulated by a consensus process.

GPs have a critically important role in managing the interface between population screening and personalised care. This role includes identifying and advising those who should opt off the NBCSPThe National Bowel Cancer Screening Program. An Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease. because of the presence of major comorbidities and limited life expectancy and those who should defer participation for several months because of recent surgery or major illness.

Practice pointA recommendation on a subject that is outside the scope of the search strategy for the systematic review, based on expert opinion and formulated by a consensus process.

Participation in a population screening program is not recommended for people with symptoms such as rectal bleeding or persistent change in bowel habit or with iron-deficiency anaemia, nor for those who should be having regular surveillance or screening based on colonoscopy, e.g. for past colorectal cancer or adenoma, chronic inflammatory bowel disease, a strong family history of colorectal cancer, or a high-risk genetic cancer syndrome (see Risk and screening based on family history of colorectal cancer).

Practice pointA recommendation on a subject that is outside the scope of the search strategy for the systematic review, based on expert opinion and formulated by a consensus process.

Individuals who have had a high-quality colonoscopy performed within the previous two years should allow another two years to elapse (i.e. skip a round) before participating in their next round of iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin. screening. ColorectalReferring to the large bowel, comprising the colon and rectum. cancer will rarely be present within that interval.

Practice pointA recommendation on a subject that is outside the scope of the search strategy for the systematic review, based on expert opinion and formulated by a consensus process.

GPs have a key role in advising patients who are at average or slightly above average risk that iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin. is the preferred method of screening. They should discuss the relative harms and benefits of colonoscopy and discourage inappropriate use of colonoscopy as a screening method.

Practice pointA recommendation on a subject that is outside the scope of the search strategy for the systematic review, based on expert opinion and formulated by a consensus process.

Participants with positive iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin. results should have follow-up investigation unless there was a clear breach in protocol when samples were collected (e.g. menstrual blood loss close to the time of sample collection). Repeating the iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin. test after a positive result carries the risk of a falsely negative test result on the second occasion because of low levels of bleeding from a cancer or adenoma, intermittent bleeding, or uneven distribution of blood in the stools.

Practice pointA recommendation on a subject that is outside the scope of the search strategy for the systematic review, based on expert opinion and formulated by a consensus process.

ColonoscopyAn examination of the large bowel using a camera on a flexible tube, which is passed through the anus. should be performed as promptly as possible after a positive iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin. to minimise the risk of psychological harm, although there is no evidence that prognosis is worsened within 120 days if cancer is present.

Considerations in making these recommendations

The recommendation for iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin. every 2 years, starting at age 50 years and continuing to age 74 years, is based on effectiveness, cost-effectiveness, the balance of benefits to harms and feasibility within the current Australian health care system. A previous analysis with ‘Policy1-Bowel’ model found that with current levels of participation, the NBCSPThe National Bowel Cancer Screening Program. An Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease. is expected to prevent 92,200 cancer cases and 59,000 deaths over the period 2015-2040; an additional 24,300 and 37,300 cases and 16,800 and 24,800 deaths would be prevented if participation was increased to 50% and 60%, respectively.[43] In 2020, an estimated 101,000 program-related colonoscopies will be performed, associated with approximately 270 adverse events; an additional 32,500 and 49,800 colonoscopies and 88 and 134 adverse events would occur if participation was increased to 50% and 60%, respectively. The overall number-needed-to-screen (NNS) is 647-788 per death prevented, with NNC of 52-59 colonoscopies per death prevented. The program is highly cost-effective due to the cancer treatment costs averted (cost-effectiveness ratio compared to no screening, A$2,000-3,000/life-year saved) and is expected to become cost saving by 2029, with A$1.7, A$2.0 and A$2.1 billion in savings accrued (2015 prices) between 2030–2040, at participation rates of 40%, 50% and 60%, respectively.

We used a comprehensive validated model to simulate the NBCSPThe National Bowel Cancer Screening Program. An Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease.. The analysis of 14 screening scenarios showed that only iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin. every 2 years, and CT colonographyAlso known as virtual colonoscopy, a medical imaging procedure that uses low dose radiation CT scanning to obtain an interior view of the colon (the large bowel) that is otherwise only seen with a more invasive procedure where an endoscope is inserted into the rectum and passed through the entire colon. every 10 years, were cost-effective at all three levels of participation and that iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin. every 2 years (as used in the current NBCSPThe National Bowel Cancer Screening Program. An Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease.) had a cost-effectiveness ratio of $2,000–$3,000 per life–year saved as well as a favourable profile with respect to the NNC.

Applicability to the Australian setting

The ‘Policy1-Bowel’ model was used to simulate the NBCSPThe National Bowel Cancer Screening Program. An Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease. and alternative screening approaches. Calculated rates of colorectal cancer incidence and mortality, survival figures for colorectal cancer, the probability of dying from other causes and population size and projected size were all derived from Australian data. The costs of screening, investigation and stage-specific treatment all related to Australia. In addition, cost-effectiveness assessment related to the willingness-to-pay threshold of $AUD 50,000 per life–year saved used in Australia.

These findings relate to population screening in Australia. Their applicability to other countries will depend on similarities to Australia, including level of risk for colorectal cancer and the design and costs of their health services.

Balance of benefits and harms

The risks of screening include potential psychological adverse effects, which range from the trauma of identifying disease in symptom-free, healthy individuals, to stress experienced by people in whom cancer is suspected although later discounted, to more subtle concerns of participants during the screening process.[44] Healthcare professionals must recognise the potential adverse psychological effects of screening, although several studies have shown no evidence of long-term harm after screening.[45][46][47] These potential adverse effects are balanced by avoiding the distress associated with diagnosis of an advanced cancer when there has been no opportunity for early detection by screening.

Choice of target age range for population screening

The age range for organised population screening continues to be 50–74 years, based on considerations of effectiveness, cost-effectiveness and the balance of benefits to harms.

When assessing changes to the screening age, reducing the starting age of 45 years was cost-effective, but with a much less favourable ratio of benefits to harms than for 50–74 years and required a substantially higher number of colonoscopies for each extra cancer death prevented.

Since screening from age 50–74 years was both more effective and cost-effective, resources would be better invested in increasing participation in the existing NBCSPThe National Bowel Cancer Screening Program. An Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease. target age group rather than in starting screening at the age of 45 years. ScreeningPerforming tests to identify disease in people before any symptoms appear. after 74 years of age was not found to be cost-effective and is not recommended.

Choice of testing interval for population screening

The recommendation not to increase the current frequency of testing is based on the modelling study findings that annual testing with iFOBTs would not be a cost-effective screening strategy in the Australian setting.

Modelling indicated that testing with iFOBTs every 2 years is a very cost-effective screening strategy for colorectal cancer in the Australian setting.

Choice of immunochemical occult blood test as preferred screening test for population screening

Faecal occult blood tests versus flexible sigmoidoscopy or CT colonographyAlso known as virtual colonoscopy, a medical imaging procedure that uses low dose radiation CT scanning to obtain an interior view of the colon (the large bowel) that is otherwise only seen with a more invasive procedure where an endoscope is inserted into the rectum and passed through the entire colon.

Population-based screening using faecal occult blood tests or flexible sigmoidoscopy can reduce colorectal cancer-specific mortality. While both methods of screening are effective, there are major concerns about feasibility, acceptability, and cost-effectiveness with flexible sigmoidoscopy.

While the literature review demonstrated the effectiveness of flexible sigmoidoscopy for population screening, it has several disadvantages. Its acceptability to health professionals and the target population is unclear in Australia. Participants are likely to request sedation, which substantially increases costs. Requests for flexible sigmoidoscopy may result in complete colonoscopy instead. Population screening based on flexible sigmoidoscopy would not be feasible in Australia because of the lack of dedicated facilities and staff to support such a program, the high capital cost of developing those facilities, problems of access related to travel times for participants living in outer regional, rural and remote areas. Modelling indicated that screening based on flexible sigmoidoscopy would not be cost-effective.

The high level of cost effectiveness for CT colonographyAlso known as virtual colonoscopy, a medical imaging procedure that uses low dose radiation CT scanning to obtain an interior view of the colon (the large bowel) that is otherwise only seen with a more invasive procedure where an endoscope is inserted into the rectum and passed through the entire colon. should be interpreted in the light of a limited evidence base for long-term outcomes after CT colonographyAlso known as virtual colonoscopy, a medical imaging procedure that uses low dose radiation CT scanning to obtain an interior view of the colon (the large bowel) that is otherwise only seen with a more invasive procedure where an endoscope is inserted into the rectum and passed through the entire colon. screening. Furthermore, we were unable to fully take into account infrastructure investments and costs that would be required. CT colonographyAlso known as virtual colonoscopy, a medical imaging procedure that uses low dose radiation CT scanning to obtain an interior view of the colon (the large bowel) that is otherwise only seen with a more invasive procedure where an endoscope is inserted into the rectum and passed through the entire colon. was not considered to be a feasible option for population screening, as a substantial increase in infrastructure, capacity and workforce would be necessary.

Immunochemical versus guaiac occult blood tests

There is supporting high-level evidence from one RCTA study in which people are allocated at random (by chance alone) to receive one of several clinical interventions. One of these interventions is the standard of comparison or control. of iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin.,[12] three large RCTs evaluating screening with guaiac faecal occult blood test (gFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin.)[1][2][3] from the 1990s, as well as three case-control studies[48][49][50] on the effectiveness of FOBT as a population-based screening modality.

The success of iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin. screening for colorectal cancer in the Australian population was reported in the 2012 Analysis of Bowel Cancer Outcomes for the National Bowel Cancer Screening ProgramAn Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease..[51] In this report, colorectal cancer mortality was compared between people in the NBCSPThe National Bowel Cancer Screening Program. An Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease. invitee and the never-invited groups in an intention-to-screen colorectal cancer mortality analysis. Of the 10,080 never-invited people with a colorectal cancer diagnosis, 1,973 (19.6%) had died of colorectal cancer before 2012. Of the 2,609 people in the NBCSPThe National Bowel Cancer Screening Program. An Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease. invitee group with a colorectal cancer diagnosis, 298 (11.4%) had died of colorectal cancer by the same date: hazard ratio (HR) 1.77; 95% confidence interval (CI) 1.57 to 2.00. When corrected for potential lead-time bias in screen-detected cancers, the risk of death from colorectal cancer was still significantly higher in the never-invited group (hazard ratio 1.15, 95% CI: 1.01–1.31). The mean follow-up time to bowel cancer death for all diagnoses was 18.6 months (range 0–64.3 months, standard deviation 13.9 months).

To date, there has been only one high-level published RCTA study in which people are allocated at random (by chance alone) to receive one of several clinical interventions. One of these interventions is the standard of comparison or control. that compared iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin.-based screening with no screening.[12] With the widespread availability of evidence-based colorectal cancer screening in many countries including Australia (National Bowel Cancer Screening ProgramAn Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease. [NBCSPThe National Bowel Cancer Screening Program. An Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease.]), it would be unethical to initiate new randomised controlled trials to compare screening by iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin. with no screening.[52]

Whilst population-based trials of iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin. have not been as comprehensive as for gFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin., the European guidelines for quality assurance in colorectal cancer screening and diagnosis (2010)[53] recommend population screening with iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin. over gFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin. on the basis of:

iFOBTs used as a screening modality for colorectal cancer will also detect a significant proportion of advanced adenomas in the average-risk population. Removal of advanced adenomas at colonoscopy should reduce the future incidence of colorectal cancer.

Health system implications of the recommendations

Clinical practice

Implementation of the recommendation to continue the current NBCSPThe National Bowel Cancer Screening Program. An Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease. strategy for screening in the average-risk population (iFOBTA test that can detect microscopic amounts of blood in stools. Types of FOBT include immunochemical FOBTs (iFOBTs), which directly detect haemoglobin using antibodies specific for the globin moiety of human haemoglobin, and guaiac FOBTs (gFOBTs), which detect peroxidase activity, an indirect method for identification of haemoglobin. every 2 years, at age 50–74 years) will not result in any change in clinical practice.

GPs have a critically important role in managing the interface between population screening and personalised care, identifying and advising those who should opt off because of major co-morbidities and limited life expectancy, the presence of special risk factors, recent colonoscopy for whatever reason, and those who should defer the invitation until they recover from recent surgery or major illness.

GPs are able to promote and substantially boost participation in the NBCSPThe National Bowel Cancer Screening Program. An Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease.. Other key roles include explaining the significance of positive screening test results, arranging colonoscopy, discussing any further action that needs to be taken as well as interacting with the central register.

ColonoscopyAn examination of the large bowel using a camera on a flexible tube, which is passed through the anus. services urgently need to introduce booking systems within a model of care that give priority to these and other high-risk groups to put this into effect.

Resourcing

Implementation of the screening recommendations will not result in any change from the resource requirements already predicted.

Resourcing considerations for implementation of the recommendations include:

continued expansion of the NBCSPThe National Bowel Cancer Screening Program. An Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease. to complete rollout of screening every two years by 2020

expansion of public awareness campaigns and promotion of the NBCSPThe National Bowel Cancer Screening Program. An Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease. to GPs to boost participation rates

exploration of alternative screening pathways to boost participation rates in the Indigenous population and other disadvantaged groups.

It would be highly desirable to establish centralised adenoma registers to evaluate the extent and significance of detection of adenomas in the NBCSPThe National Bowel Cancer Screening Program. An Australian screening program that aims to reduce illness and death from bowel cancer through early detection or prevention of the disease., to predict the likely contribution of adenoma resection to incidence and mortality reduction in colorectal cancer, and to support quality improvement in the high volume and costly area of colonoscopic post-polypectomy surveillance.

Barriers to implementation

No new barriers to the implementation of the screening recommendations are envisaged.

Existing barriers to participation in FOBT screening fall into several categories, including inconvenience of the testing process, aversion to manipulating faeces, lack of perceived benefit of screening, fear of a diagnosis of cancer, cost, views about personal invulnerability, and cultural beliefs and attitudes.[55][56] Recent studies have demonstrated that several of these barriers can be at least partially overcome so as to improve participation.[57][58][59]

The use of iFOBTs, which require no change in diet or medication, simplifying the method of stool sampling, and endorsement of screening by a person’s own GPA medical professional who treats acute and chronic illnesses and provides preventive care and health education to a wide range of patients. all lead to a significant improvement in participation.[57][58][59]

Appropriate public education and promotion is usually necessary to enhance participation rates.

In Australia, weather conditions and geographic factors may affect performance of iFOBTs.[60][61] High temperatures and delays to sample analysis may each reduce test sensitivity for cancer and advanced adenomas. This is of special importance in remote regions where return of postal items may be slow and throughout Australia during hot summer months.